Category Archives: Wings

Cutting a round inspection access panel hole

Hours: 2

One of the things that the factory forgot as part of the change from the Sling 4 to the Sling TSi was the required access to the internals of the wing next to the Pitot tube.

In the Sling TSi design, some inspection panels were removed including the one next to the Pitot tube. By itself, if someone was building the wings from scratch, that might be fine as long as the builder installs the Pitot tube beforehand and doesn’t anticipate to ever need to access it, such as if using an unheated Pitot tube.

However, I am going to use the Garmin heated & regulated Pitot tube, which not only requires wires to be run to the Pitot tube, but also that I need to mount the regulator unit next to it.

Since I ordered the quickbuild, I ordered it with this specification, but unfortunately the factory didn’t receive the Pitot tube from their supplier in time and shipped my kit without installing it.

So after I received my shipment and inspected everything, I realized that installing this after the fact wasn’t going to be easy, particularly with the lack of a hole in the wing. Unfortunately the factory also forgot to run the wiring to the pitot tube, which creates a whole second issue, for which I’ve been working on a solution.

I informed the factory a while ago and also gave Matthew, one of the other TSi builders a heads-up since he hadn’t started on the wings yet. The factory realized their mistake in the plans and promised to come up with a solution and send me instructions and a plan.

Drafting a plan

While I was waiting for the factory to come up with a plan, I actually started drawing up my own plans to fabricate the entire inspection panel myself and used it as an opportunity to learn and use Solidworks, which I can use for free as part of being an EAA member.
Initial draft of the panel on paper My panel design in Solidworks

Since I had the chance to chat with Mike Blyth at Oshkosh for a while and we chatted about my build, I mentioned that I was still waiting for the factory to come up with a plan for the inspection cover and he promised that he’d check on the progress when he got back to South Africa and indeed, two weeks later, I got an email with the plans.

The factory plans, in keeping with the other inspection access panels, uses the same flush round inspection cover that is used to access the Flaps and Aileron connecting rods.

Factory plans for the new inspection access panel

Since I am still busy with other things in the build and haven’t actually made my own panel yet, I am going to go with the factory plans that they have drawn up for me.

Cutting a round inspection access panel hole

There is just one difficulty to overcome – the access panel is round and large and I don’t think there are 143.4 mm drill bits I can buy in Home depot.

After a bit of research, I found a solution in using a drill attachment sheet metal nibbler that can cut around a center pivot and can attach to my Milwaukee hand drill.

Since this is quite an operation, I decided to get some practice with the tool on a piece of spare aluminum and also made a video of it, since I figured that it might be helpful for other builders in the future.

I started by marking out the circle using a drafting compass. It’s been quite a few years, but luckily I still remembered how to use it and how to find the center of the circle again by making two marks. Proof that you may indeed use what you’ve learned in geometry class sometime in life, even if it’s 15 years later. After that I clamped the piece of metal on the edge of the table.

I drilled the center pivot hole to 1/8th of an inch, which makes the pivot sit in the hole and then measured out the starting hole for the drill, make a starter hole and then used a step drill bit to upsize the hole until it aligned with my marked circle.

After that, I set up the drilling tool with the pivot and made sure that the outside of the cutting bit aligns with my circle and then attached the drill and went to work.

Here are a couple of pictures of the first circle I cut – note that briefly I had the pivot point jump out of the hole, which caused me to waver a bit which you can see towards the bottom where it’s not perfectly round, so make sure the pivot continues to stay in the hole.

Marking out the circle using a compass Clamping down the metal on the table Cut hole and the inside disk - I did waver a little bit on the bottom as I didn't hold the pivot in place perfectly for a moment. So practicing this will pay off to not repeat the mistake. Inspection cover "test fit" Tools used to cut the access panel

Annotated video of the process of cutting the hole

 

Finishing the Flaps

Hours: 6

With the ribs for the Flaps out of the way, I am ready to finish the flaps. First order of business is to ensure that I have the ribs all in the right order.
Completed ribs laid out along the right Flap

Once that was figured out, I first clecoed the ribs in place to the bottom of the skins and then closed up the skins and clecoed the top as well.
Ribs clecoed in place to the bottom of the Flaps skin Clecos in place to close up the right Flap

After checking that everything is aligning properly with the skins, I started riveting the skin. The top side is pretty straightforward. For the bottom side, there are a couple of tight spots next to the hinges, so the close quarter rivet wedge came in handy for a couple of the rivets.

Rivets in place Close quarter rivet wedge to rivet the tight space next to the hinge Bottom right side Flap ready to rivet Bottom right side flap almost done riveting

With the right side Flap finished and closed up, I then repeated it all for the left side Flap. There was also a couple of the edges where the hinges sit that needed a bit of deburring attention.
Some deburring was needed for the hole where the hinges go through Upside down view of the left side Flap ribs clecoed in place Almost done with the left side Flap riveting

After I finished the top skins, I did one quick alignment test fit on the wings and everything looked good, so then I finished up both sides by riveting the front rivet lane that closes the skin against the other side.
Front line ready to close up the skins of the Flaps for good Almost done riveting the Flaps Completed left Flap Both Flaps completed

Final alignment check

Once I finished all the riveting, I did one final test fit onto the wings. I used a bit of mason string and my laser level and everything is looking good. Now onto finishing the Elevator.
Final test fitting and alignment checks Final test fitting and alignment checks

Timelapse of building the Flaps

Getting started with riveting the Flaps

Hours: 2.5

With the priming of the Flaps ribs out of the way, I got started riveting the Flaps. First order of business was laying out all the ribs in the correct order.
Flaps ribs laid out in the correct order

After laying out the ribs in the correct order, I started laying out the right hinges to go with each rib. There is one interesting rib that needs to be riveted in two steps as one part goes on top of the other:
Hinge and bracket to be riveted onto the rib Ready to rivet those 3 rivets that will hide under the angled bracket Ready to rivet the bracket on top of the hinge

Once I figured all of that out of the right side Flaps, I repeated the steps for the left side Flaps:
Right side ribs done and laying out the left side

I received the missing rivets for the assembly the other day, so now I was able to finish the riveting all of the hinges to the ribs to actually complete the flaps.Completed ribs laid out along the right Flap

 

Flaps priming & Aileron inventory

Hours: 4

After having completed the inventory and preparing the edges and holes of the Flaps the other day, I went ahead to prime them so I can start assembling them.

As it turns out, cleaning the parts is a great time to chat with my mom over the phone, so she got to watch while I sat on my stool to give the parts a scrub using some Simple Green Cleaner to get them ready for priming.
Flaps parts laid out ready to clean Flaps parts ready for priming

Once that was done, I unfolded my small paint booth and primed all the ribs of the flaps.
Ready to prime the Flaps ribs Flaps ribs primed

Aileron parts inventory

With the Flaps primer drying, I moved on to unpack the Aileron parts and prepare them to prime next.

Unfortunately one set of ribs have some dents from the factory, so I will need replacements for those. The other parts were okay and just needed the usual treatment of deburring some of the edges and holes.
Dents in Aileron rib 2 Dents in Aileron rib 2

Then I went on a scavenger hunt to try to find an Eyebolt and Nut to go with the ribs as they weren’t in any of the bags of the Aileron assembly and eventually I figured that it might be on the pushrod that it threads into and I remembered that I have a separate Tube labelled Control Pushrods. So after opening that tube and pulling out a well packed bubble-wrap bundle I eventually found the rods for the Ailerons, and while I was at it, also the Flaps and attached to them were the Eyebolts and the nut mentioned.
Eyebolt mentioned in the Aileron assembly

The last thing I could not find, were the AN4-16A bolts, which are mentioned in the assembly instructions, but were not in the shipping manifest, so I added a request for those bolts together with the replacement for the damaged ribs.
I also found that I don’t have any 4.8x10mm rivets (HW-RIV-163) which I need for the Flaps assembly and those were also missing in the packing list, but need to be able to rivet some of the hinges onto the Flaps.

Hopefully I can get those replacements and missing parts soon so I can cut down on half-ready assemblies between the Elevator, Flaps & Ailerons.
Aileron parts laid out after I finished inspecting and deburring everything

Flaps & Aileron inventory and parts inspection

Hours: 2

I’m currently still waiting for the correct Elevator ribs from the Factory before I can continue to complete the Empennage. So in the meantime I’ve moved on to get started on the Wings. First order of business is the Ailerons and Flaps, starting with doing the inventory and parts check.

First I had to find the sub assemblies for the Flaps and Ailerons in the Wings crate. After a bit of digging, I got all the bags that had to do with those two parts out and then starting laying them out to check them off the packing list.
Wing crate opened and time to dig out the parts for the Flaps and Ailerons Skins for Flaps and Ailerons present

Once I had all the bags laid out, I started to check them off the inventory checklist and got out my tools for deburring a couple of sharp edges and holes.
Bags of Flap assembly parts ready to be checked Bags of Aileron assembly ready to be checked

I confirmed that I got all the parts out of the crate and went back once to find the Aileron balance tubes. Then I started to get going on removing the protective plastic from the Flaps parts and inspecting the parts, marking each part along the way. There were a couple of sharp edges and holes, but by and large most parts were good to go.
Inspecting and labeling the Flaps ribs Done with inspecting and deburring all the parts of the Flaps